We explore the fine structure of the holographic entanglement entropy proposal (the Ryu-Takayanagi formula) in ${\mathrm{AdS}}_3/{\mathrm{CFT}}_2$. With the guidance from the boundary and bulk modular flows we find a natural slicing of the entanglement wedge with the modular planes, which are codimension one bulk surfaces tangent to the modular flow everywhere. This gives an one-to-one correspondence between the points on the boundary interval $\mathcal{A}$ and the points on the Ryu-Takayanagi (RT) surface ${\mathcal{E}}_{\mathcal{A}}$. In the same sense an arbitrary subinterval ${\mathcal{A}}_2$ of $\mathcal{A}$ will correspond to a subinterval ${\mathcal{E}}_2$ of ${\mathcal{E}}_{\mathcal{A}}$. This fine correspondence indicates that the length of ${\mathcal{E}}_2$ captures the contribution $s_{\mathcal{A}}({\mathcal{A}}_2)$ from ${\mathcal{A}}_2$ to the entanglement entropy $S_{\mathcal{A}}$, hence gives the contour function for entanglement entropy. Furthermore we propose that $s_{\mathcal{A}}({\mathcal{A}}_2)$ in general can be written as a simple linear combination of entanglement entropies of single intervals inside $\mathcal{A}$. This proposal passes several nontrivial tests.

We compute the entanglement entropy in a composite system separated by a finitely ramified boundary with the structure of a self-similar lattice graph. We derive the entropy as a function of the decimation factor which determines the spectral dimension, the latter being generically different from the topological dimension. For large decimations, the graph becomes increasingly dense, yielding a gain in the entanglement entropy which, in the asymptotically smooth limit, approaches a constant value. Conversely, a small decimation factor decreases the entanglement entropy due to a large number of spectral gaps which regulate the amount of information crossing the boundary. In line with earlier studies, we also comment on similarities with certain holographic formulations. Finally, we calculate the higher order corrections in the entanglement entropy which possess a log-periodic oscillatory behavior.

We analyze the edge mode structure of Euclidean three-dimensional gravity from within the quantum theory as embodied by a Ponzano-Regge–Turaev-Viro discrete state sum with York-Gibbons-Hawking boundary conditions. This structure is encoded in a pair of dual statistical models of the vertex and face kind, which for specific choices of boundary conditions turn out to be integrable. The duality is just the manifestation of a pervasive dual structure which manifests at different levels of the classical and quantum theories. Emphasis will be put on the geometrical interpretation of the edge modes which leads, in particular, to the identification of the quantum analogue of Carlip’s would-be normal diffeomorphisms. Due to the presence of a quantum mechanical length gap, the boundary structures we identify are discrete. Finally, we also provide a reinterpretation of our construction in terms of a non-Abelian $2+1$ topological phase with electric boundary conditions.

In $D=2+1$ dimensions, elementary particles of a given helicity can be described by local Lagrangians (parity singlets). By means of a “soldering” procedure, two opposite helicities can be joined together and give rise to massive spin-$s$ particles carrying both helicities $\pm s$ (parity doublets), and such Lagrangians can also be used in $D=3+1$ to describe massive spin-$s$ particles. From this point of view the parity singlets (self-dual models) in $D=2+1$ are the building blocks of real massive elementary particles in $D=3+1$. In the three cases $s=1$, $3/2$, 2 there are $2s$ self-dual models of order $1,2,\dots ,2s$ in derivatives. In the spin-3 case the fifth order model is missing in the literature. Here we deduce a fifth order spin-3 self-dual model and fill up this gap. It is shown to be ghost free by means of a master action which relates it with the top model of sixth order. We believe that our approach can be generalized to arbitrary integer spin-$s$ in order to obtain the models of order $2s$ and $2s-1$. We also comment on the difficulties in relating the fifth order model with their lower order duals.

We analyze a four-parameter class of asymptotically flat magnetized solutions to the Einstein-Maxwell equations constructed by Manko et al. and show that these represent systems of two corotating extreme black holes with equal masses and electric charges, and opposite magnetic and NUT charges, connected by a cosmic string. We discuss several three-parameter subclasses and determine in each case the parameter domain in which the ring singularity is absent. We find a two-parameter subclass and a one-parameter subclass where the conical singularity is also absent in the horizon corotating frame.

A natural question arises from observable signatures of scalar, fermion, and vector degrees of freedom (d.o.f.) in our Universe along with spin 2 symmetric tensor field in the form of gravity: why is our Universe is free of any perceptible signature of massless antisymmetric tensor modes? This work brings out a natural explanation of these phenomena through higher curvature quantum d.o.f. in the gravity sector that were dominant in the early universe. In the backdrop of a $F(R)$ gravity model, we propose how the scalar d.o.f. associated with higher curvature term in the model can generate a heavily suppressed coupling between any antisymmetric massless modes and various standard model fields.

The complex path (or Hamilton-Jacobi) approach to Hawking radiation corresponds to the intuitive picture of particles tunneling through the horizon and forming a thermal radiation. This method computes the tunneling rate of a given particle from its equation of motion and equates it to the Boltzmann distribution of the radiation from which the Hawking temperature is identified. In agreement with the original derivation by Hawking and the other approaches, it has been checked, case by case, that the temperature is indeed universal for a number of backgrounds and the tunneling of particles mostly from spins 0 to 1 and, in some instances, from spins $3/2$ and 2. In this article, we give a general proof that the temperature is indeed equal for all (massless and massive) particles with spins from 0 to 2 on backgrounds satisfying a specific separation ansatz (and limited to be Einstein for spin greater than 1) in any number of dimensions. Moreover, we propose a general argument to extend this result to any spin greater than 2.

Observations of redshifted 21-cm signal from neutral hydrogen (HI) appear to be the most promising probe of the cosmic dark ages. The signal carries information about the thermal state along with density distribution of the inter galactic medium (IGM). The cosmic microwave background radiation (CMBR), through its interaction with charged particles, plays a major role in determining the kinetic and spin temperature of HI gas in the IGM during dark ages. A spatially fluctuating ionization fraction, which is caused by inhomogeneous recombinations, causes heat transfer from the CMBR to the IGM gas inhomogeneous. We revisit the impact of this inhomogeneous heat transfer on spatial fluctuations in the observed HI 21-cm signal over a large redshift range during dark ages. Our study shows that the effect negatively impacts fluctuations in the HI spin temperature and results in an enhanced HI 21-cm power spectrum. We find that the effect is particularly important during the transition of the gas kinetic temperature being coupled to the CMBR to fully decoupled from it, i.e., in the redshift range $30\lesssim z\lesssim 300$. It is found that, on the average the HI power spectrum, $P_{T_b}(k,z)$ is enhanced by $\sim 4\%$, $\sim 10\%$, $\sim 20\%$, and $\sim 30\%$ at redshifts 60, 90, 140, and 200 respectively at $k=0.1{\mathrm{Mpc}}^{-1}$. The effect becomes even more significant at lower values of $k_{\parallel }^2/k^2$ due to the reduced dominance of the peculiar velocity. It is observed that the power spectrum is enhanced by $\sim 49\%$ and $\sim 93\%$ at redshifts 140 and 200 respectively at $k=0.1{\mathrm{Mpc}}^{-1}$ for $k_{\parallel }^2/k^2=0$. This enhancement has a weak $k$-mode dependence.

At the end of inflation, the inflaton field decays into an initially nonthermal population of relativistic particles which eventually thermalize. We consider the production of dark matter via freeze-in from this relativistic plasma, focusing on the prethermal phase. We find that for a production cross section $\sigma (E)\sim E^n$ with $n>2$, the present dark matter abundance is produced during the prethermal phase of its progenitors. For $n\le 2$, entropy production during reheating makes the nonthermal contribution to the present dark matter abundance subdominant compared to that produced thermally. As specific examples, we verify that the nonthermal contribution is irrelevant for gravitino production in low scale supersymmetric models ($n=0$) and is dominant for gravitino production in high scale supersymmetry models ($n=6$).

The EDGES experiment has observed an absorption feature in the global 21 cm spectrum with a surprisingly large amplitude. These results can be explained by decreasing the kinetic temperature of baryons, which could be achieved through the scattering between the baryons and cold dark matter particles. It seems that the most researched dark matter annihilation model is not able to explain such a large amplitude, since the interactions between the particles produced by the dark matter annihilation and the particles that have been present in the Universe could increase the baryonic temperature. Recently, C. Feng and G. Holder have suggested that the large amplitude in the global 21 cm spectrum could be produced by considering the possible excess of the early radio radiation. In this paper, we propose that the dark matter annihilation still works to explain the large amplitude observed by the EDGES experiment. Even including the dark matter annihilation, the large absorption amplitude in the global 21 cm spectrum can be produced by considering the possible excess of the early radio radiation.

The recent results of the EDGES Collaboration indicate that during the era of reionization, the primordial gas was much colder than expected. The cooling of the gas could be explained by interactions between dark matter (DM) and particles in the primordial gas. Constraints from cosmology and particle experiments indicate that this DM should be light ($\sim 10–80\mathrm{MeV}$), carry a small charge ($\epsilon \sim {10}^{-6}–{10}^{-4}$), and only make up a small fraction of the total amount of DM. Several constraints on the DM parameter space have already been made. We explore the yet unconstrained region in the case that the millicharged DM makes up $\sim 2\%$ of the total dark matter, through the scenario in which this DM annihilates only into mu and tau neutrinos. We set upper limits on the annihilation cross section using the Super-Kamiokande data, and predict the limits that could be obtained through Hyper-Kamiokande, JUNO and DUNE. We find that data from Super-Kamiokande is not yet able to constrain this model, but future experiments might be. We furthermore explore DM annihilation into solely neutrinos in general, giving an update of the current limits, and predict the limits that could be placed with future experiments.

With the corsika code, $3\times {10}^5$ extensive air showers with proton, alpha, and carbon particles as the primary particles have been simulated. The primary energy range was chosen between 1 GeV and 1 PeV with a differential flux given by $dN/dE\propto E^{-2.7}$ and zenith angles of 0° to 60°. Using the muons produced by the extensive air showers, the angular distribution of the muons has been investigated at various depths. A distribution of $\sin \theta {\cos }^{k(X_v,E)}(\theta )$ for the zenith angle of muons has been obtained such that the values of $k(X_v,E)$ are found for different atmospheric vertical depths, $X_v$, and energies, $E$, using the simulation data. We obtained $k(X_v;E)=(0.4494\pm 0.0046)\ln (X_v/{\mathrm{g}\mathrm{cm}}^{-2})+(-0.4903\pm 0.0079)\ln (E/\mathrm{GeV})$ with a regression of 95%.

There are multiple techniques to determine the chemical composition of the ultrahigh-energy cosmic rays. While most of the methods are primarily sensitive to the average atomic mass, it is challenging to discriminate between the two lightest elements: proton and helium. In this paper, the proton-to-helium ratio in the energy range $10^{18.0}\mathrm{eV}$ to $10^{19.3}\mathrm{eV}$ is estimated using the tail of the distribution of the depth of the shower maximum $X_{\max }$. Using the exponential decay scale $\mathrm{\Lambda }$ measured by the Pierre Auger Observatory and the Telescope Array experiment we derive the 68% CL constraints on the proton-to-helium ratio $\mathrm{p}/\mathrm{He}>7.3$ and $\mathrm{p}/\mathrm{He}>0.43$ for $10^{18.0}<E<10^{18.5}\mathrm{eV}$ and $10^{18.3}<E<10^{19.3}\mathrm{eV}$ correspondingly. It is shown that the result is conservative with respect to the admixture of heavier elements. We evaluate the impact of the hadronic interaction model uncertainty. The implications for the astrophysical models of the origin of cosmic rays and the safety of the future colliders are discussed.

In this paper, we explore first necessary steps to construct a fully massive version of a variable-flavor number scheme. In particular we focus, as an example, on an extension of the five-flavor scheme, where instead of neglecting explicit initial state quark mass effects, we retain all massive dependence, while keeping the resummation properties of the massless five-flavor scheme. We name this scheme the five-flavor-massive scheme. Apart from consistently modified parton distribution functions, we provide all the ingredients that are needed to implement this scheme at MC@NLO accuracy, in a Monte Carlo event generator. As proof of concept we implement this scheme in sherpa and perform a comparison of the new scheme with traditional ones for the simple process of scalar particle production in bottom-quark fusion.

Nuggets—very large stable bound objects arising in the presence of a sufficiently attractive and long-range force and in the absence of a dark Coulomb force—are a smoking gun signature for asymmetric dark matter (ADM). The cosmology of ADM nuggets is both generic and unique: nuggets feature highly exothermic fusion processes, which can impact the shape of the core in galaxies, as well as give rise to rare dark star formation. We find, considering the properties of nuggets in a generic extended nuclear model with both attractive and repulsive forces, that self-interaction constraints place an upper bound on nugget masses at the freeze-out of synthesis in the ballpark of $M_{\mathrm{fo}}\lesssim {10}^{16}\mathrm{GeV}$. We also show that indirect detection strongly constrains models where the scalar mediator binding the nuggets mixes with the Higgs.

Higgs decays to gauge boson pairs are a crucial ingredient in the study of Higgs properties, with the decay $H\to \gamma \gamma$ being particularly sensitive to new physics effects. Assuming all potential new physics occurs at energies far above the weak scale, deviations from standard model predictions can be parametrized in terms of the coefficients of a standard model effective field theory (SMEFT). When experimental limits on the SMEFT coefficients reach an accuracy of a few percent, predictions must be done beyond the lowest order in the SMEFT in order to match theory and experimental accuracy. This paper completes a program of computing the one-loop electroweak SMEFT corrections to $H\to V{V}^{\prime }$, $V=W^{\pm }$, $Z$, $\gamma$. The calculation of the real contribution to $H\to W^{+}{W}^{-}\gamma$ is performed by mapping two-loop amplitudes to the three-body phase space.

We explore leptoquark production and decay for the ${\tilde{R}}_2$ class of models at the proposed $e^{-}p$ collider LHeC, planned to operate with 150 GeV electron and 7 TeV proton beams. In addition to the coupling of the leptoquark with the lepton and jet, the model also has right-handed neutrinos coupled to the leptoquark. We analyze the collider signatures of a number of final states that can originate from leptoquark decay into the standard model particles, as well as the final states that originate from further decay of the heavy neutrinos produced from the leptoquark. We find that the final state ${\ell }^{-}+n-\text{jets}(1\le n\le 2)$ has the largest discovery prospect, more than $5\sigma$ with only a few ${\mathrm{fb}}^{-1}$ of data to probe a leptoquark of mass 1.1 TeV, even with a generic set of cuts. The significance falls sharply with increasing leptoquark mass. However, with $100{\mathrm{fb}}^{-1}$ of data, a $5\sigma$ discovery for leptoquarks of mass up to 1.4 TeV is still achievable. Also, for the same luminosity final state $\overline{b}{\ell }^{+}{\tau }^{-}+n-\text{jets}(n\ge 2)+{\cancel{E}}_T$, resulting from the cascade decay of the leptoquark to a $\overline{t}$ and right-handed neutrino, followed by further decays of $\overline{t}$ and the neutrino, is expected to yield a rather large number of events ($\approx 180$).

We present results on QCD with four dynamical flavors in the temperature range $150\mathrm{MeV}\lesssim T\lesssim 500\mathrm{MeV}$. We have performed lattice simulations with Wilson fermions at maximal twist and measured Polyakov loop, chiral condensate and disconnected susceptibility, on lattices with spacings as fine as 0.065 fm. For most observables spacing effects are below statistical errors, which enables us to identify lattice results with continuum estimates. Our estimate of the pseudocritical temperature compares favorably with continuum results from staggered and domain wall fermions, confirming that a dynamical charm does not contribute in the transition region. From the high-temperature behavior of the disconnected chiral susceptibility we infer the topological susceptibility, which encodes relevant properties of the QCD axion, a plausible dark matter candidate. The topological susceptibility thus measured exhibits a power-law decay for $T/T_c\gtrsim 2$, with an exponent close to the one predicted by the dilute instanton gas approximation (DIGA). Close to $T_c$ the temperature-dependent effective exponent seems to approach the DIGA result from above, a behavior which would support recent analytic calculations based on an instanton-dyon model. These results constrain the mass of a hypothetical QCD post-inflationary axion, once an assumption concerning the relative contribution of axions to dark matter is made.